The present disclosure relates to an image forming apparatus including a function for detecting aerial discharge between a photoconductor and a developing body.
In general, an electrophotographic image forming apparatus includes a developing device that includes a developing body for carrying toner, and a bias applying circuit. The bias applying circuit applies, between a photoconductor and the developing body, a developing bias voltage in which an AC voltage and a DC voltage are superimposed. The developing device executes a developing process for developing an electrostatic latent image on the photoconductor by using the toner carried by the developing body.
When the image forming apparatus is used in a low atmospheric pressure environment such as a high-altitude region, aerial discharge tends to occur between the photoconductor and the developing body. When the aerial discharge occurs, surface potential of the photoconductor is disturbed and image quality deteriorates. Generally, the aerial discharge is referred to as leakage.
The image forming apparatus includes a function for executing a developing bias adjustment process to prevent the aerial discharge from occurring. The developing bias adjustment process is executed to gradually increase the AC voltage in the developing bias voltage until the aerial discharge occurs, and then, based on the level of the AC voltage when the aerial discharge occurs, the developing bias adjustment process sets the level of the AC voltage in the developing bias voltage during execution of the developing process.
It is possible to detect occurrence of the aerial discharge by detecting a direct current flowing through the bias applying circuit, the circuit for applying the developing bias voltage between the photoconductor and the developing body.
The image forming apparatus, before being shipped, is installed in a standard environment in which conditions such as atmospheric pressure, temperature, and humidity are at predetermined standard states. The image forming apparatus executes the developing bias adjustment process in the standard environment. This allows for the level of the AC voltage in the developing bias voltage during execution of the developing process to be set at a standard level suitable for the standard environment.
Furthermore, in a state where the image forming apparatus is installed in its place of use, a serviceperson or a user executes a predetermined adjustment start operation on the image forming apparatus. The image forming apparatus executes the developing bias adjustment process in response to the adjustment start operation.
By executing the developing bias adjustment process in a state where the image forming apparatus is installed in its place of use, the level of the AC voltage in the developing bias voltage during execution of the developing process is updated from the standard level to a level suitable for the usage environment.